Enable and disable comparator voltage reference

ABSTRACT

This document discusses, among other things, systems and methods to reduce power use of an accessory detection device. The accessory detection device can be configured to be coupled to a mobile device having an audio jack configured to be coupled to a mobile device accessory having a send/end key. In an example, the accessory detection device can include a comparator and a switch. The comparator can be configured to receive mobile device accessory information from the mobile device accessory and to determine activation of the send/end key using the received mobile device accessory information. The switch can be configured to receive connection information indicative of mobile device accessory connection to the audio jack and to isolate a reference input of the comparator from a supply voltage using the connection information, for example, to reduce leakage current.

CLAIM OF PRIORITY

This application claims the benefit of priority under 35 U.S.C. §119(e)of Seth M. Prentice et al. U.S. Provisional Patent Application Ser. No.61/416,245, entitled “ENABLE AND DISABLE COMPARATOR VOLTAGE REFERENCE,”filed on Nov. 22, 2010, which is incorporated by reference herein in itsentirety.

BACKGROUND

Mobile devices (e.g., mobile phones, etc.) can include variousaccessories. For example, mobile devices with audio jacks can beconfigured to be coupled to a headset having at least one of aheadphone, a speaker, a microphone, or a send/end key. In an example,the mobile device can include a comparator configured to identify whenthe send/end key is activated on the headset. In certain examples,activating the send/end key can reduce the microphone bias to ground orincrease the microphone bias to a full microphone bias voltage level. Inan example, a voltage divider can be used to set the comparatorthreshold level to identify the send/end key activation. In manydevices, the resistors used for the voltage divider are connected to asupply that is normally enabled, even if the headset is not connected,creating excess current draw.

OVERVIEW

This document discusses, among other things, systems and methods toreduce power use of an accessory detection device. The accessorydetection device can be configured to be coupled to a mobile devicehaving an audio jack configured to be coupled to a mobile deviceaccessory having a send/end key. In an example, the accessory detectiondevice can include a comparator and a switch. The comparator can beconfigured to receive mobile device accessory information from themobile device accessory and to determine activation of the send/end keyusing the received mobile device accessory information. The switch canbe configured to receive connection information indicative of mobiledevice accessory connection to the audio jack and to isolate a referenceinput of the comparator from a supply voltage using the connectioninformation, for example, to reduce leakage current.

This overview is intended to provide an overview of subject matter ofthe present patent application. It is not intended to provide anexclusive or exhaustive explanation of the invention. The detaileddescription is included to provide further information about the presentpatent application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates generally an example of a system including anaccessory detection device.

FIG. 2 illustrates generally an example of a system including anaccessory detection device and an external resistor divider.

FIG. 3 illustrates generally an example of a system including anaccessory detection device, a baseband processor, an audio codec,applications processor, and an audio jack.

FIG. 4 illustrates generally an example of a logic diagram for anaccessory detection device.

FIG. 5 illustrates generally an example of a standard PMOS device.

FIG. 6 illustrates generally an example of a PMOS device designed forelectrostatic discharge (ESD) robustness.

DETAILED DESCRIPTION

The present inventors have recognized, among other things, systems andmethods to detect connection of one or more mobile device accessories toa mobile device, for example, to an audio jack of the mobile device orone or more other inputs or outputs. In an example, an accessorydetection device (e.g., a circuit configured to be placed inside of themobile device) can include a comparator and a microphone switch with anexternal voltage reference pin. In an example, the accessory detectiondevice can include enable/disable circuitry that can recognize when thevoltage reference is or is not required. When the voltage reference isnot required, a switch can isolate the detection device from a supplyvoltage, in certain examples eliminating excess leakage current andincreasing the battery life of the mobile device. In an example,integrating a standard PMOS gate to isolate the detection device fromthe supply voltage can introduce electrostatic discharge (ESD) concerns.Accordingly, in certain examples, the detection device can include acustomized PMOS cell configured to increase ESD robustness whitemaintaining functionality.

FIG. 1 illustrates generally an example of a system 100 including acomparator 105, a switch 110, and a resistor divider including first andsecond resistors 111, 112. In an example, the comparator 105 can beconfigured to receive a reference voltage at a reference input (+) andmobile device accessory information, such as information from amicrophone pin of a mobile device accessory (e.g., a headset, etc.), ata microphone input (J_MIC), to compare the mobile device accessoryinformation to the reference voltage and to provide an indication of asend/end key activation using the comparison (e.g., using a send/end key(S/E) output).

In an example, the switch 110 can be configured to receive connectioninformation indicative of mobile device accessory connection to theaudio jack, for example, at a control input (CTRL) and to isolate areference input of the comparator from a supply voltage (VDD) using theconnection information. In an example, the switch 110 can include ametal-oxide field-effect transistor (MOSFET), such as a p-type MOSFET(PMOS) device, and in certain examples, as described below, the PMOS orother device can include an ESD PMOS device configured to alleviate ESDconcerns found in typical PMOS devices.

FIG. 2 illustrates generally an example of a system 200 including anaccessory detection device 101 and an external resistor dividerincluding first and second resistors 111, 112. In an example, thedetection device 101 can include a comparator 105 and a switch 110. Inan example, the switch 110 can include a PMOS device or other switchconfigured to isolate a supply voltage (VDD) from the external resistordivider and the comparator 105. In an example, an integrated circuit(IC) can include the detection device 101 and not the external resistordivider, such as to allow a determinable reference voltage at areference input (REF) of the comparator using the first and secondresistors 111, 112.

FIG. 3 illustrates generally an example of a system 300 including anaccessory detection device 101, a baseband processor 130, an audio codec131, an applications processor 132, and an audio jack 125.

In an example, the audio jack 125 can include four terminals, such as:(1) left audio (L); (2) right audio (R); (3) ground (GND); and (4) adata terminal. In an example, the data terminal can be configured toreceive mobile device accessory information, such as a microphone input(Mic). In other examples, the data terminal can be configured to receiveor provide other accessory information, such as providing video dataout, etc.

In certain examples, the audio jack 125 can be configured to receive anaudio plug 135, such as a 4-pole audio plug. In other examples, theaudio jack 125 can be configured to receive one or more other types ofaudio plugs, or the audio jack 125 and audio plug 135 can be replacedwith one or more other type of input/output (IO).

In an example, when a headset is plugged into the audio jack 125, abaseband processor 130 can enable the detection device 101, for example,using an enable input (EN) and an enable circuit 115, and can close amicrophone switch 116, connecting a microphone pin (MIC) to a microphoneinput (J_MIC), such as by using a select (SEL) input, which can enablethe detection device 101 to provide a voltage reference at a referencesupply voltage (R_VDD) for the comparator 105, such as through anexternal resistor divider (e.g., the first and second resistors 111,112) configured to provide a determinable (e.g., user determinable,etc.) reference voltage to the comparator 105.

In the example of FIG. 3, a microphone line between the audio codec 131and the detection device 101 can be pulled to a microphone bias(MIC_Bias) level through a microphone resistor (R_(MIC), e.g., typically2.2 kΩ). In an example, a headset microphone (e.g., a JFET typemicrophone, etc.) can represent a load of ˜2 kΩ, creating a microphonebias level of ˜MIC_Bias/2. In an example, if a send/end (S/E) key isactivated (e.g., pushed) on the headset, the connection to themicrophone can be open allowing the microphone bias to increase to ornear the full microphone bias voltage potential. The microphone bias canpass the reference voltage on the comparator 105 and the send/enable(S/E) output pin on the detection device 101 can be updated,communicating an S/E key activation to the baseband processor 130.

In an example, the circuitry (e.g., the switch 110) and the referencevoltage (REF) on the comparator 105 can be required only when a headsetis plugged in. If a video switch (VID) is selected, for example, from anapplications processor 132, or the detection device 101 is disabled, thereference supply voltage (R_VDD) can be disabled using the switch 110,eliminating excess current through the external resistor divider (e.g.,the first and second resistors 111, 112), etc.

FIG. 4 illustrates generally an example of a timing diagram 400 of adetection device, such as that illustrated in the example of FIG. 3,disclosing an example relationship between a supply voltage (VDD) 141,an enable signal (EN) 142, a reference supply voltage (R_VDD) 143, aselect signal (SEL) 144, a microphone signal (MIC) 145, a comparatoroutput (COMP) 146, and a video enable signal (VID) 147 with reference totime. In an example, at 166, the detection device can be enabled and theMIC switch can be selected. In an example, at 167, the detection devicecan be enabled, and the VII) switch can be selected. In an example, at168, the detection device can be disabled. Table 1, below, provides anexample operation.

TABLE 1 EN SEL MIC VID R_VDD S/E 0 X 3-State 3-State GND H 1 1 J_MICOpen VDD Active 1 0 Open J_MIC GND H

FIG. 5 illustrates generally an example of a standard PMOS device 500.

FIG. 6 illustrates generally an example of a p-type metal-oxidefield-effect transistor (PMOS) device 600 designed for electrostaticdischarge (ESD) robustness. The PMOS device 600 between the supplyvoltage (VDD) and a reference supply voltage (R_VDD) can provide ESDrobustness while still meeting application requirements (e.g., for theexample illustrated in FIG. 3). In an example, the PMOS device 600includes increased source metal 170 and increased drain metal 171 incomparison to the standard PMOS device 500 of FIG. 5. In certainexamples, the channel lengths and widths are increased with respect tothe example illustrated in FIG. 5. Further, the number of stripes hasincreased, as well as the source contact to gate spacing (SCGS) 172 andthe drain contact to gate spacing (DCGS) 173, greatly increasing thecurrent density in the PMOS device 500. Table 2 illustrates examplechanges for each of the parameters referenced above.

TABLE 2 Parameter Standard PMOS ESD PMOS Channel Length 0.35 um 0.50 umChannel Width   80 um  400 um Number of Stripes   4   12 SCGS/DCGSSpacing 0.30 um 1.80 um Current Density 6.40 ma 57.0 mA

Although certain examples above are illustrated with respect to a mobiledevice, an audio jack, and a headset, the subject matter disclosedherein is likewise applicable to any comparator configured to compare areceived signal to a reference voltage supplied using a supply voltage.In an example, the supply voltage can be isolated or coupled to thecomparator using information about the received signal, or usinginformation about a device providing the received signal.

Additional Notes

In Example 1, a system includes an accessory detection device configuredto be coupled to a mobile device having an audio jack, wherein the audiojack is configured to be coupled to a mobile device accessory having asend/end key. The accessory detection device can include a comparatorconfigured to receive mobile device accessory information from themobile device accessory and to determine activation of the send/end keyusing the received mobile device accessory information and a switchconfigured to receive connection information indicative of a mobiledevice accessory connection to the audio jack and to isolate a referenceinput of the comparator from a supply voltage using the connectioninformation.

In Example 2, Example 1 can optionally include the audio jack, whereinthe audio jack includes a 4-pole audio jack configured to receive a4-pole audio plug, the 4-pole audio jack including left audio terminal,a right audio terminal, a ground terminal, and a data terminal, whereinthe switch is optionally configured to receive connection informationusing the ground terminal of the 4-pole audio jack, and wherein theconnection information is optionally different than the mobile deviceaccessory information.

In Example 3, the comparator of any one or more of Examples 1-2 isoptionally configured to receive mobile device accessory informationusing the data terminal.

In Example 4, the switch of any one or more of Examples 1-3 isoptionally configured to isolate the reference input of the comparatorfrom the supply voltage response to the connection informationindicating that the mobile device accessory is not coupled to the audiojack.

In Example 5, the switch of any one or more of Examples 1-4 isoptionally configured to couple the reference input of the comparator tothe supply voltage in response to the connection information indicatingthat the mobile device accessory is coupled to the audio jack.

In Example 6, any one or more of Examples 1-5 optionally includes aresistor divider configured to receive a voltage from the switch and toprovide a reference voltage to the reference input of the comparator.

In Example 7, any one or more of Examples 1-6 optionally includes anintegrated circuit (IC) including the comparator and the switch, and thecomparator of any one or more of Examples 1-6 is optionally configuredto receive a determinable reference voltage at the reference input usingan external resistor divider and the switch.

In Example 8, any one or more of Examples 1-7 optionally includes theexternal resistor divider, including first and second resistors havingfirst and second resistance values, wherein the of any one or more ofExamples 1-7 optionally includes a switch output and a reference input,wherein the first resistor of any one or more of Examples 1-7 isoptionally coupled between the switch output and the reference input,wherein the second resistor of any one or more of Examples 1-7 isoptionally coupled between the reference input and a voltage level, andwherein the switch of any one or more of Examples 1-7 is optionallyconfigured to selectively provide the supply voltage to the externalresistor divider to provide the determinable reference voltage to thereference input of the comparator as a function of the first and secondresistance values and the supply voltage.

In Example 9, the mobile device accessory of any one or more of Examples1-8 optionally includes at least one of a 4-pole mobile device headsethaving a send/end key or a 4-pole audio/video interface configured toprovide audio or video output from the mobile device to an externaldisplay.

In Example 10, the switch of any one or more of Examples 1-9 optionallyincludes a metal-oxide-semiconductor field-effect transistor (MOSFET).

In Example 11, the switch of any one or more of Examples 1-10 optionallyincludes a p-channel MOSFET (PMOS) device.

In Example 12, the PMOS device of any one or more of Examples 1-11optionally includes an electrostatic-discharge (ESD) PMOS device havinga channel width at least 500 times greater than a channel length and asource-contact to gate spacing and a drain-contact to gate spacing atleast 3 times greater than the channel length to provide a desiredcurrent density and ESD robustness.

In Example 13, any one or more of Examples 1-12 can include receivingconnection information indicative of mobile device accessory connectionto an audio jack of a mobile device, receiving mobile device accessoryinformation, different from the connection information, from the mobiledevice accessory at a comparator, determining activation of a send/endkey of the mobile device accessory using the comparator and the mobiledevice accessory information, and isolating a reference input of thecomparator from a supply voltage using the connection information and aswitch.

In Example 14, the receiving connection information of any one or moreof Examples 1-13 optionally includes receiving connection informationfrom a ground terminal of a 4-pole audio jack configured to receive a4-pole audio plug of the mobile device accessory.

In Example 15, the isolating the reference input of the comparator ofany one or more of Examples 1-14 optionally includes in response to theconnection information indicating that the mobile device accessory isnot coupled to the audio jack.

In Example 16, any one or more of Examples 1-15 optionally includescoupling the reference input of the comparator to the supply voltage inresponse to the connection information indicating that the mobile deviceaccessory is coupled to the audio jack.

In Example 17, any one or more of Examples 1-16 optionally includesselectively providing a determinable reference voltage to the referenceinput of the comparator using a resistor divider coupled to the switch,the resistor divider optionally including first and second resistorshaving first and second resistance values, the reference voltagedeterminable as a function of the first and second resistance values.

In Example 18, the isolating the reference input of the comparator ofany one or more of Examples 1-17 using the switch optionally includesusing a metal-oxide-semiconductor field-effect transistor (MOSFET).

In Example 19, the isolating the reference input of the comparator usingthe MOSFET of any one or more of Examples 1-18 optionally includes usinga p-channel MOSFET (PMOS) device.

In Example 20, the isolating the reference input of the comparator usingthe PMOS device of any one or more of Examples 1-19 optionally includesusing an electrostatic-discharge (ESD) PMOS device having a channelwidth at least 500 times greater than a channel length and asource-contact to gate spacing and a drain-contact to gate spacing atleast 3 times greater than the channel length to provide a desiredcurrent density and ESD robustness. In other examples, one or more otherranges can be provided to provide a desired current density and ESDrobustness, with space and cost tradeoffs.

In Example 21, a system or apparatus can include, or can optionally becombined with any portion or combination of any portions of any one ormore of Examples 1-20 to include, means for performing any one or moreof the functions of Examples 1-20, or a machine-readable mediumincluding instructions that, when performed by a machine, cause themachine to perform any one or more of the functions of Examples 1-20.

The above detailed description includes references to the accompanyingdrawings, which form apart of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” All publications, patents, and patent documentsreferred to in this document are incorporated by reference herein intheir entirety, as though individually incorporated by reference. In theevent of inconsistent usages between this document and those documentsso incorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein.” Also, in the following claims, theterms “including” and “comprising” are open-ended, that is, a system,device, article, or process that includes elements in addition to thoselisted after such a term in a claim are still deemed to fall within thescope of that claim. Moreover, in the following claims, the terms“first,” “second,” and “third,” etc. are used merely as labels, and arenot intended to impose numerical requirements on their objects.

The above description is intended to be illustrative, and notrestrictive. For example, although the examples above have beendescribed relating to p-type devices, one or more examples can beapplicable to n-type devices. In other examples, the above-describedexamples or one or more aspects thereof) may be used in combination witheach other. Other embodiments can be used, such as by one of ordinaryskill in the art upon reviewing the above description. The Abstract isprovided to comply with 37 CFR, §1.72(b), to allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A system comprising: an accessory detectiondevice configured to be coupled to a mobile device having an audio jack,wherein the audio jack is configured to be coupled to a mobile deviceaccessory having a send/end key, the accessory detection deviceincluding: a comparator configured to receive mobile device accessoryinformation from the mobile device accessory and to determine activationof the send/end key using the received mobile device accessoryinformation; and a switch configured to receive connection informationindicative of a mobile device accessory connection to the audio jack andto isolate a reference input of the comparator from all supply voltageusing the connection information.
 2. The system of claim 1, includingthe audio jack, wherein the audio jack includes a 4-pole audio jackconfigured to receive a 4-pole audio plug, the 4-pole audio jackincluding left audio terminal, a right audio terminal, a groundterminal, and a data terminal; wherein the switch is configured toreceive connection information using the ground terminal of the 4-poleaudio jack; and wherein the connection information is different than themobile device accessory information.
 3. The system of claim 2, whereinthe comparator is configured to receive mobile device accessoryinformation using the data terminal.
 4. The system of claim 1, whereinthe switch is configured to isolate the reference input of thecomparator from the supply voltage in response to the connectioninformation indicating that the mobile device accessory is not coupledto the audio jack.
 5. The system of claim 1, wherein the switch isconfigured to couple the reference input of the comparator to the supplyvoltage in response to the connection information indicating that themobile device accessory is coupled to the audio jack.
 6. The system ofclaim 1, including a resistor divider configured to receive a voltagefrom the switch and to provide a reference voltage to the referenceinput of the comparator.
 7. The system of claim 1, including anintegrated circuit (IC) including the comparator and the switch; andwherein the comparator is configured to receive a determinable referencevoltage at the reference input using an external resistor divider andthe switch.
 8. The system of claim 7, including the external resistordivider, the external resistor divider including first and secondresistors having first and second resistance values; wherein the ICincludes a switch output and a reference input; wherein the firstresistor is coupled between the switch output and the reference input,and wherein the second resistor is coupled between the reference inputand a voltage level; and wherein the switch is configured to selectivelyprovide the supply voltage to the external resistor divider to providethe determinable reference voltage to the reference input of thecomparator as a function of the first and second resistance values andthe supply voltage.
 9. The system of claim 1, wherein the mobile deviceaccessory includes at least one of a 4-pole mobile device headset havinga send/end key or a 4-pole audio/video interface configured to provideaudio or video output from the mobile device to an external display. 10.The system of claim 1, wherein the switch includes ametal-oxide-semiconductor field-effect transistor (MOSFET).
 11. Thesystem of claim 10, wherein the switch includes a p-channel MOSFET(PMOS) device.
 12. The system of claim 11, wherein the PMOS deviceincludes an electrostatic-discharge (ESD) PMOS device having a channelwidth at least 500 times greater than a channel length and asource-contact to gate spacing and a drain-contact to gate spacing atleast 3 times greater than the channel length to provide a desiredcurrent density and ESD robustness.
 13. A method comprising: receivingconnection information indicative of mobile device accessory connectionto an audio jack of a mobile device; receiving mobile device accessoryinformation, different from the connection information, from the mobiledevice accessory at a comparator; determining activation of a send/endkey of the mobile device accessory using the comparator and the mobiledevice accessory information; and isolating a reference input of thecomparator from all supply voltage using the connection information anda switch.
 14. The method of claim 13, wherein the receiving connectioninformation includes receiving connection information from a groundterminal of a 4-pole audio jack configured to receive a 4-pole audioplug of the mobile device accessory.
 15. The method of claim 13, whereinthe isolating the reference input of the comparator includes in responseto the connection information indicating that the mobile deviceaccessory is not coupled to the audio jack.
 16. The method of claim 13,including coupling the reference input of the comparator to the supplyvoltage in response to the connection information indicating that themobile device accessory is coupled to the audio jack.
 17. The method ofclaim 13, including selectively providing a determinable referencevoltage to the reference input of the comparator using a resistordivider coupled to the switch, the resistor divider including first andsecond resistors having first and second resistance values, thereference voltage determinable as a function of the first and secondresistance values.
 18. The method of claim 13, wherein the isolating thereference input of the comparator using the switch includes using ametal-oxide-semiconductor field-effect transistor (MOSFET).
 19. Themethod of claim 18, wherein the isolating the reference input of thecomparator using the MOSFET includes using a p-channel MOSFET (PMOS)device.
 20. The method of claim 19, wherein the isolating the referenceinput of the comparator using the PMOS device includes using anelectrostatic-discharge (ESD) PMOS device having a channel width atleast 500 times greater than a channel length and a source-contact togate spacing and a drain-contact to gate spacing at least 3 timesgreater than the channel length to provide a desired current density andESD robustness.